Thin 3D Fan-Out Embedded Wafer Level Package (EWLB) for Application Processor and Memory Integration

ABSTRACT

A semiconductor device has a plurality of first semiconductor die with an encapsulant deposited over a first surface of the first semiconductor die and around the first semiconductor die. An insulating layer is formed over the encapsulant and over a second surface of the first semiconductor die opposite the first surface. The insulating layer includes openings over the first semiconductor die. A first conductive layer is formed over the first semiconductor die within the openings. A second conductive layer is formed over the first conductive layer to form vertical conductive vias. A second semiconductor die is disposed over the first semiconductor die and electrically connected to the first conductive layer. A bump is formed over the second conductive layer outside a footprint of the first semiconductor die. The second semiconductor die is disposed over an active surface or a back surface of the first semiconductor die.

CLAIM TO DOMESTIC PRIORITY

The present application claims the benefit of U.S. ProvisionalApplication No. 61/608,402, filed Mar. 8, 2012, which application isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of forming afan-out embedded wafer level ball grid array (Fo-eWLB) including a thinfilm interconnect structure having fine pitch interconnects.

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, charged-coupled devices (CCDs), solar cells, anddigital micro-mirror devices (DMDs).

Semiconductor devices perform a wide range of functions such as signalprocessing, high-speed calculations, transmitting and receivingelectromagnetic signals, controlling electronic devices, transformingsunlight to electricity, and creating visual projections for televisiondisplays. Semiconductor devices are found in the fields ofentertainment, communications, power conversion, networks, computers,and consumer products. Semiconductor devices are also found in militaryapplications, aviation, automotive, industrial controllers, and officeequipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The atomic structure of semiconductor material allows itselectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed calculations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing, and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each semiconductor die is typicallyidentical and contains circuits formed by electrically connecting activeand passive components. Back-end manufacturing involves singulatingindividual semiconductor die from the finished wafer and packaging thedie to provide structural support and environmental isolation. The term“semiconductor die” as used herein refers to both the singular andplural form of the words, and accordingly can refer to both a singlesemiconductor device and multiple semiconductor devices.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller semiconductor die sizecan be achieved by improvements in the front-end process resulting insemiconductor die with smaller, higher density active and passivecomponents. Back-end processes may result in semiconductor devicepackages with a smaller footprint by improvements in electricalinterconnection and packaging materials.

Another goal of semiconductor manufacturing is to produce higherperformance semiconductor devices. Increases in device performance canbe accomplished by forming electrical interfaces that are capable ofoperating at higher speeds. Higher operating speeds can be achieved byshortening signal path lengths within the semiconductor device package.One approach to achieving the objectives of greater integration andsmaller, higher-speed semiconductor devices is to focus on threedimensional (3D) packaging technologies including package-on-package(PoP). The electrical interconnection between devices in a semiconductorstructure and external devices can be accomplished with conductivethrough silicon vias (TSV) or through hole vias (THV).

The vertical z-direction interconnect of a THV substrate consumes space,increases the overall height of the package, and imposes highermanufacturing costs. The thickness of a THV substrate limits the extentby which the signal path length and overall package thickness can bereduced. The signal path length in a THV substrate limits the speed andelectrical performance of the semiconductor device. A conventional THVsubstrate is 250 micrometers (μm) to 350 μm thick. The thickness of theTHV substrate leads to warpage and reduced thermal performance. Further,the vias in a THV substrate are often formed by laser drilling whichlimits the via pitch that can be achieved in the THV substrate. Aconventional THV substrate has a via pitch of 100 μm or greater. Theminimum achievable via pitch within a THV substrate is insufficient formounting high density semiconductor devices and limits the flexibilityof semiconductor device integration in the 3D semiconductor structures.

SUMMARY OF THE INVENTION

A need exists for a thin interconnect structure with reduced packageheight and more finely pitched interconnects. Accordingly, in oneembodiment, the present invention is a method of making a semiconductordevice comprising the steps of providing a plurality of firstsemiconductor die, depositing an encapsulant over a first surface of thefirst semiconductor die and around the first semiconductor die, formingan insulating layer over the encapsulant and over a second surface ofthe first semiconductor die opposite the first surface, forming a firstconductive layer over the insulating layer, and disposing a secondsemiconductor die over the first semiconductor die and electricallyconnected to the first conductive layer.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a plurality offirst semiconductor die, depositing an encapsulant over the firstsemiconductor die, forming an insulating layer including openings overthe first semiconductor die, forming a first conductive layer over thefirst semiconductor die, and disposing a second semiconductor die overthe first semiconductor die and electrically connected to the firstconductive layer.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a firstsemiconductor die, forming a first insulating layer over the firstsemiconductor die, forming a first conductive layer over the firstsemiconductor die, and disposing a second semiconductor die over thefirst semiconductor die.

In another embodiment, the present invention is a semiconductor devicecomprising a plurality of first semiconductor die and a first insulatinglayer including openings formed over the first semiconductor die. Afirst conductive layer is formed the first semiconductor die. A secondsemiconductor die disposed over the first semiconductor die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a printed circuit board (PCB) with different types ofpackages mounted to its surface;

FIGS. 2 a-2 c illustrate further detail of the representativesemiconductor packages mounted to the PCB;

FIGS. 3 a-3 c illustrate a semiconductor wafer with a plurality ofsemiconductor die separated by a saw street;

FIGS. 4 a-4 n illustrate a process of forming a Fo-eWLB including a thinfilm interconnect structure having fine pitch interconnects andsemiconductor die mounted to opposing sides of the thin filminterconnect structure;

FIGS. 5 a-5 n illustrate a process of forming a Fo-eWLB including a thinfilm interconnect structure having fine pitch interconnects and asemiconductor die mounted over a TSV semiconductor die; and

FIGS. 6 a-6 g illustrate an alternative embodiment of the process offorming a Fo-eWLB.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, resistors, and transformers,create a relationship between voltage and current necessary to performelectrical circuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devices,transforming the semiconductor material into an insulator, conductor, ordynamically changing the semiconductor material conductivity in responseto an electric field or base current. Transistors contain regions ofvarying types and degrees of doping arranged as necessary to enable thetransistor to promote or restrict the flow of electrical current uponthe application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition can involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

The layers can be patterned using photolithography, which involves thedeposition of light sensitive material, e.g., photoresist, over thelayer to be patterned. A pattern is transferred from a photomask to thephotoresist using light. In one embodiment, the portion of thephotoresist pattern subjected to light is removed using a solvent,exposing portions of the underlying layer to be patterned. In anotherembodiment, the portion of the photoresist pattern not subjected tolight, the negative photoresist, is removed using a solvent, exposingportions of the underlying layer to be patterned. The remainder of thephotoresist is removed, leaving behind a patterned layer. Alternatively,some types of materials are patterned by directly depositing thematerial into the areas or voids formed by a previous deposition/etchprocess using techniques such as electroless and electrolytic plating.

Patterning is the basic operation by which portions of the top layers onthe semiconductor wafer surface are removed. Portions of thesemiconductor wafer can be removed using photolithography, photomasking,masking, oxide or metal removal, photography and stenciling, andmicrolithography. Photolithography includes forming a pattern inreticles or a photomask and transferring the pattern into the surfacelayers of the semiconductor wafer. Photolithography forms the horizontaldimensions of active and passive components on the surface of thesemiconductor wafer in a two-step process. First, the pattern on thereticle or masks is transferred into a layer of photoresist. Photoresistis a light-sensitive material that undergoes changes in structure andproperties when exposed to light. The process of changing the structureand properties of the photoresist occurs as either negative-actingphotoresist or positive-acting photoresist. Second, the photoresistlayer is transferred into the wafer surface. The transfer occurs whenetching removes the portion of the top layers of semiconductor wafer notcovered by the photoresist. The chemistry of photoresists is such thatthe photoresist remains substantially intact and resists removal bychemical etching solutions while the portion of the top layers of thesemiconductor wafer not covered by the photoresist is removed. Theprocess of forming, exposing, and removing the photoresist, as well asthe process of removing a portion of the semiconductor wafer can bemodified according to the particular resist used and the desiredresults.

In negative-acting photoresists, photoresist is exposed to light and ischanged from a soluble condition to an insoluble condition in a processknown as polymerization. In polymerization, unpolymerized material isexposed to a light or energy source and polymers form a cross-linkedmaterial that is etch-resistant. In most negative resists, the polymersare polyisopremes. Removing the soluble portions (i.e. the portions notexposed to light) with chemical solvents or developers leaves a hole inthe resist layer that corresponds to the opaque pattern on the reticle.A mask whose pattern exists in the opaque regions is called aclear-field mask.

In positive-acting photoresists, photoresist is exposed to light and ischanged from relatively nonsoluble condition to much more solublecondition in a process known as photosolubilization. Inphotosolubilization, the relatively insoluble resist is exposed to theproper light energy and is converted to a more soluble state. Thephotosolubilized part of the resist can be removed by a solvent in thedevelopment process. The basic positive photoresist polymer is thephenol-formaldehyde polymer, also called the phenol-formaldehyde novolakresin. Removing the soluble portions (i.e. the portions exposed tolight) with chemical solvents or developers leaves a hole in the resistlayer that corresponds to the transparent pattern on the reticle. A maskwhose pattern exists in the transparent regions is called a dark-fieldmask.

After removal of the top portion of the semiconductor wafer not coveredby the photoresist, the remainder of the photoresist is removed, leavingbehind a patterned layer. Alternatively, some types of materials arepatterned by directly depositing the material into the areas or voidsformed by a previous deposition/etch process using techniques such aselectroless and electrolytic plating.

Depositing a thin film of material over an existing pattern canexaggerate the underlying pattern and create a non-uniformly flatsurface. A uniformly flat surface is required to produce smaller andmore densely packed active and passive components. Planarization can beused to remove material from the surface of the wafer and produce auniformly flat surface. Planarization involves polishing the surface ofthe wafer with a polishing pad. An abrasive material and corrosivechemical are added to the surface of the wafer during polishing. Thecombined mechanical action of the abrasive and corrosive action of thechemical removes any irregular topography, resulting in a uniformly flatsurface.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual semiconductor die and then packaging thesemiconductor die for structural support and environmental isolation. Tosingulate the semiconductor die, the wafer is scored and broken alongnon-functional regions of the wafer called saw streets or scribes. Thewafer is singulated using a laser cutting tool or saw blade. Aftersingulation, the individual semiconductor die are mounted to a packagesubstrate that includes pins or contact pads for interconnection withother system components. Contact pads formed over the semiconductor dieare then connected to contact pads within the package. The electricalconnections can be made with solder bumps, stud bumps, conductive paste,or wirebonds. An encapsulant or other molding material is deposited overthe package to provide physical support and electrical isolation. Thefinished package is then inserted into an electrical system and thefunctionality of the semiconductor device is made available to the othersystem components.

FIG. 1 illustrates electronic device 50 having a chip carrier substrateor printed circuit board (PCB) 52 with a plurality of semiconductorpackages mounted on its surface. Electronic device 50 can have one typeof semiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 1 for purposes of illustration.

Electronic device 50 can be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 can be a subcomponent of a largersystem. For example, electronic device 50 can be part of a cellularphone, personal digital assistant (PDA), digital video camera (DVC), orother electronic communication device. Alternatively, electronic device50 can be a graphics card, network interface card, or other signalprocessing card that can be inserted into a computer. The semiconductorpackage can include microprocessors, memories, application specificintegrated circuits (ASIC), logic circuits, analog circuits, RFcircuits, discrete devices, or other semiconductor die or electricalcomponents. Miniaturization and weight reduction are essential for theproducts to be accepted by the market. The distance betweensemiconductor devices must be decreased to achieve higher density.

In FIG. 1, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate carrier. Second levelpackaging involves mechanically and electrically attaching theintermediate carrier to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including bond wire package 56 and flipchip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, dual in-line package(DIP) 64, land grid array (LGA) 66, multi-chip module (MCM) 68, quadflat non-leaded package (QFN) 70, and quad flat package 72, are shownmounted on PCB 52. Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using less expensive componentsand a streamlined manufacturing process. The resulting devices are lesslikely to fail and less expensive to manufacture resulting in a lowercost for consumers.

FIGS. 2 a-2 c show exemplary semiconductor packages. FIG. 2 aillustrates further detail of DIP 64 mounted on PCB 52. Semiconductordie 74 includes an active region containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and are electricallyinterconnected according to the electrical design of the die. Forexample, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements formedwithin the active region of semiconductor die 74. Contact pads 76 areone or more layers of conductive material, such as aluminum (Al), copper(Cu), tin (Sn), nickel (Ni), gold (Au), or silver (Ag), and areelectrically connected to the circuit elements formed withinsemiconductor die 74. During assembly of DIP 64, semiconductor die 74 ismounted to an intermediate carrier 78 using a gold-silicon eutecticlayer or adhesive material such as thermal epoxy or epoxy resin. Thepackage body includes an insulative packaging material such as polymeror ceramic. Conductor leads 80 and bond wires 82 provide electricalinterconnect between semiconductor die 74 and PCB 52. Encapsulant 84 isdeposited over the package for environmental protection by preventingmoisture and particles from entering the package and contaminatingsemiconductor die 74 or bond wires 82.

FIG. 2 b illustrates further detail of BCC 62 mounted on PCB 52.Semiconductor die 88 is mounted over carrier 90 using an underfill orepoxy-resin adhesive material 92. Bond wires 94 provide first levelpackaging interconnect between contact pads 96 and 98. Molding compoundor encapsulant 100 is deposited over semiconductor die 88 and bond wires94 to provide physical support and electrical isolation for the device.Contact pads 102 are formed over a surface of PCB 52 using a suitablemetal deposition process such as electrolytic plating or electrolessplating to prevent oxidation. Contact pads 102 are electricallyconnected to one or more conductive signal traces 54 in PCB 52. Bumps104 are formed between contact pads 98 of BCC 62 and contact pads 102 ofPCB 52.

In FIG. 2 c, semiconductor die 58 is mounted face down to intermediatecarrier 106 with a flipchip style first level packaging. Active region108 of semiconductor die 58 contains analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed according to the electrical design of the die.For example, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements withinactive region 108. Semiconductor die 58 is electrically and mechanicallyconnected to carrier 106 through bumps 110.

BGA 60 is electrically and mechanically connected to PCB 52 with a BGAstyle second level packaging using bumps 112. Semiconductor die 58 iselectrically connected to conductive signal traces 54 in PCB 52 throughbumps 110, signal lines 114, and bumps 112. A molding compound orencapsulant 116 is deposited over semiconductor die 58 and carrier 106to provide physical support and electrical isolation for the device. Theflipchip semiconductor device provides a short electrical conductionpath from the active devices on semiconductor die 58 to conductiontracks on PCB 52 in order to reduce signal propagation distance, lowercapacitance, and improve overall circuit performance. In anotherembodiment, the semiconductor die 58 can be mechanically andelectrically connected directly to PCB 52 using flipchip style firstlevel packaging without intermediate carrier 106.

FIG. 3 a shows a semiconductor wafer 120 with a base substrate material122, such as silicon, germanium, gallium arsenide, indium phosphide, orsilicon carbide, for structural support. A plurality of semiconductordie or components 124 is formed on wafer 120 separated by a non-active,inter-die wafer area or saw street 126 as described above. Saw street126 provides cutting areas to singulate semiconductor wafer 120 intoindividual semiconductor die 124.

FIG. 3 b shows a cross-sectional view of a portion of semiconductorwafer 120. Each semiconductor die 124 has a back surface 128 and activesurface 130 containing analog or digital circuits implemented as activedevices, passive devices, conductive layers, and dielectric layersformed within the die and electrically interconnected according to theelectrical design and function of the die. For example, the circuit mayinclude one or more transistors, diodes, and other circuit elementsformed within active surface 130 to implement analog circuits or digitalcircuits, such as digital signal processor (DSP), ASIC, memory, or othersignal processing circuit. Semiconductor die 124 may include discretedevices. Discrete devices can be active devices, such as transistors anddiodes, or passive devices, such as capacitors, resistors, and inductorsfor RF signal processing. Semiconductor die 124 may also include apackaged semiconductor die. In one embodiment, semiconductor die 124 isa flipchip type device.

An electrically conductive layer 132 is formed over active surface 130using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 132 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 132 operates as contact padselectrically connected to the circuits on active surface 130. Conductivelayer 132 can be formed as contact pads disposed side-by-side a firstdistance from the edge of semiconductor die 124, as shown in FIG. 3 b.Alternatively, conductive layer 132 can be formed as contact pads thatare offset in multiple rows such that a first row of contact pads isdisposed a first distance from the edge of the die, and a second row ofcontact pads alternating with the first row is disposed a seconddistance from the edge of the die.

In FIG. 3 c, semiconductor wafer 120 is singulated through saw street126 using a saw blade or laser cutting tool 134 into individualsemiconductor die 124.

FIGS. 4 a-4 m illustrate a process of forming a Fo-eWLB including a thinfilm interconnect structure having fine pitch interconnects andsemiconductor die mounted to opposing sides of the thin filminterconnect structure. FIG. 4 a shows a portion of substrate or carrier150 containing temporary or sacrificial base material such as silicon,germanium, gallium arsenide, indium phosphide, silicon carbide, resin,beryllium oxide, glass, or other suitable low-cost, rigid material forstructural support. An interface layer or double-sided tape 152 isformed over carrier 150 as a temporary adhesive bonding film, etch-stoplayer, or release layer.

In FIG. 4 b, semiconductor die 124 from FIG. 3 c are mounted tointerface layer 152 and over carrier 150 using, for example, a pick andplace operation with active surface 130 oriented toward the carrier.

In FIG. 4 c, an encapsulant or molding compound 154 deposited overinterface layer 152 and carrier 150 and over and around semiconductordie 124 using a paste printing, compressive molding, transfer molding,liquid encapsulant molding, vacuum lamination, film-assisted molding, orother suitable applicator. Encapsulant 154 is formed over back surface128 of semiconductor die 124, and can be thinned in a subsequentbackgrinding step. Encapsulant 154 can also be deposited such that theencapsulant is coplanar with back surface 128, and does not cover theback surface. Encapsulant 154 can be polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 154 is non-conductive, provides physicalsupport, and environmentally protects the semiconductor device fromexternal elements and contaminants.

FIG. 4 d shows composite substrate or reconstituted wafer 156 covered byencapsulant 154. In FIG. 4 d, surface 158 of encapsulant 154 undergoesan optional grinding operation with grinder 160 to planarize the surfaceand reduce thickness of the encapsulant. A chemical etch can also beused to remove and planarize encapsulant 154. FIG. 4 e shows a portionof encapsulant 154 removed to expose back surface 128 of semiconductordie 124.

In FIG. 4 e, carrier 150 and interface layer 152 are removed fromcomposite substrate 156 by chemical etching, mechanical peeling,chemical mechanical planarization (CMP), mechanical grinding, thermalbake, UV light, laser scanning, or wet stripping to facilitate theformation of an interconnect structure over active surface 130 ofsemiconductor die 124 and encapsulant 154 around a periphery of thesemiconductor die.

In FIG. 4 f, an insulating or passivation layer 170 is formed oversemiconductor die 124 and encapsulant 154. Insulating layer 170 containsone or more layers of low temperature curable polymer dielectric resist(i.e., cures at less than 260 degrees Celsius (C)) with or withoutfiller, silicon dioxide (SiO2), silicon nitride (Si3N4), siliconoxynitride (SiON), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3),or other material having similar insulating and structural properties.Insulating layer 170 is deposited using PVD, CVD, printing, spincoating, spray coating, sintering, thermal oxidation, or other suitableprocess. Insulating layer 170 has a thickness of less than 10 μm and istypically as thin as 4 μm. A portion of insulating layer 170 is removedby an exposure or development process, laser direct ablation (LDA),etching, or other suitable process to form openings over conductivelayer 132. The openings expose conductive layer 132 of semiconductor die124 for subsequent electrical interconnect.

In FIG. 4 g, an electrically conductive layer 172 is patterned anddeposited over insulating layer 170, over semiconductor die 124, anddisposed within the openings in insulating layer 170 to fill theopenings and contact conductive layer 132 as one or more layers,including seed layers. The one or more layers of conductive layer 172include Al, Cu, Sn, Ni, Au, Ag, titanium (Ti)/Cu, titanium tungsten(TiW)/Cu, Ti/nickel vanadium (NiV)/Cu, TiW/NiV/Cu, or other suitableelectrically conductive material. The deposition of conductive layer 172uses PVD, CVD, electrolytic plating, electroless plating, or othersuitable process. Conductive layer 172 has a thickness of less than 15μm and is typically as thin as 3 μm. Conductive layer 172 operates as anRDL to fan-out and extend electrical connection from semiconductor die124 to points external to semiconductor die 124.

In FIG. 4 h, an insulating or passivation layer 174 is formed overinsulating layer 170 and conductive layer 172. Insulating layer 174contains one or more layers of low temperature curable polymerdielectric resist (i.e., cures at less than 260 degrees C.) with orwithout filler, SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other materialhaving similar insulating and structural properties. Insulating layer174 is deposited using PVD, CVD, printing, spin coating, spray coating,sintering, thermal oxidation, or other suitable process. Insulatinglayer 174 has a thickness of less than 10 μm and is typically as thin as4 μm. A portion of insulating layer 174 is removed by an exposure ordevelopment process, LDA, etching, or other suitable process to formopenings in the insulating layer, which expose portions of conductivelayer 172 for subsequent electrical interconnection.

In FIG. 4 i, an electrically conductive layer 176 is patterned anddeposited over insulating layer 174, over conductive layer 172, anddisposed within the openings in insulating layer 174 as one or morelayers, including seed layers, to fill the openings and contact andelectrically connect to conductive layer 172. The one or more layers ofconductive layer 176 include Al, Cu, Sn, Ni, Au, Ag, Ti/Cu, TiW/Cu,Ti/NiV/Cu, TiW/NiV/Cu, or other suitable electrically conductivematerial. The deposition of conductive layer 176 uses PVD, CVD,electrolytic plating, electroless plating, or other suitable process.Conductive layer 176 has a thickness of less than 15 μm and is typicallyas thin as 3 μm. In one embodiment, the deposition of conductive layer176 includes selective plating with a seed layer and lithography.Conductive layer 176 operates as an RDL to fan-out and extend electricalconnection from semiconductor die 124 to points external tosemiconductor die 124.

Insulating layers 170 and 174 together with conductive layers 172 and176 form thin film 178. Thin film 178 constitutes an interconnectstructure. In an alternative embodiment, thin film 178 may include asfew as one conductive layer, such as conductive layer 172. In anotheralternative embodiment, thin film 178 includes two or more RDL layers,such as conductive layers 172 and 176 and additional conductive layerssimilar to conductive layers 172 and 176. Thin film 178 may include asmany insulating and conductive layers as necessary for the interconnectdensity and electrical routing needed for the particular semiconductordevice.

Thin film 178 includes surface 180 over which semiconductor die 124 isdisposed and surface 182 opposite surface 180. Thin film 178 has athickness of less than 50 μm, which is thinner than a conventional THVsubstrate which typically has a thickness of 250 to 350 μm. Thin film178 is formed from layers of insulating and conductive material whichcan each be formed with a thickness of less than 10 μm. The thin layersof insulating and conductive material allow horizontal and verticalinterconnects to be formed in close proximity to adjacent horizontal andvertical interconnects within the thin layers (e.g., with a pitch ofless than 50 μm). With horizontal and vertical interconnects formed inclose proximity to adjacent interconnects, a higher density ofinterconnects is achieved within the interconnect structure. Becausethin film 178 includes higher density interconnects, thin film 178provides more flexibility in integration of semiconductor devices intothe 3D semiconductor structure. The high density interconnect structureaccommodates semiconductor die with varying bump pitch, for example,semiconductor die from multiple manufacturing sources.

Conductive layers 172 and 176 form horizontal and verticalinterconnections or vertical conductive vias 184 through thin film 178.Horizontal and vertical interconnections are formed as close together asnecessary for connection to a semiconductor die or component or forrouting electrical signals through thin film 178. For example,conductive layers 172 and 176 may include conductive traces. A firstconductive trace is formed in close proximity to a second conductivetrace (e.g., a pitch between conductive traces is less than 50 μm). Thefine pitch between conductive traces allows space for more conductivetraces to be formed within thin film 178, while the thinness of eachthin film layer reduces the thickness of the interconnect structurecompared to a conventional THV substrate.

Conductive layers 172 and 176 also form vertical conductive vias 184 inwhich a first vertical conductive via is formed in close proximity to asecond vertical conductive via (e.g., a pitch between verticalconductive vias is less than 50 μm). Conductive layer 172 includes afirst portion of vertical conductive vias 184, and conductive layer 176includes a second portion of vertical conductive vias 184. Verticalconductive vias 184 may extend from surface 180 to surface 182 of thinfilm 178 or vertical conductive vias 184 may be formed partially throughthin film 178. A pitch P between vertical conductive vias 184 is lessthan 50 μm. The pitch P between vertical conductive vias 184 in thinfilm 178 is finer than the pitch between conductive vias in aconventional through-hole via (THV) substrate, which is typically 100 μmor greater.

The fine pitch horizontal and vertical interconnections in thin film 178provide a higher interconnect density and input/output (I/O) terminalcount. Thin film 178 provides an interconnect pitch which allows highdensity semiconductor die to be mounted to either or both of surfaces180 and 182 of thin film 178 in a flipchip orientation. Semiconductordie can be mounted in a face-to-face orientation on thin film 178. Thinfilm 178 extends beyond a footprint of semiconductor die 124 in afan-out design to further increase the I/O terminal count. The thinnessof thin film 178 allows for a smaller and thinner overall semiconductordevice package, which reduces warpage and increases the speed of thedevice. Further, the high density interconnects accommodates moreelectrical signals per 3D semiconductor structure and improves thecompatibility of the interconnect structure with a greater variety ofsemiconductor device and components types.

In FIG. 4 j, an optional insulating or passivation layer 186 is formedover insulating layer 174 and conductive layer 176. Insulating layer 186contains one or more layers of low temperature curable polymerdielectric resist (i.e., cures at less than 260 degrees C.) with orwithout filler, SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other materialhaving similar insulating and structural properties. Insulating layer186 is deposited using PVD, CVD, printing, spin coating, spray coating,sintering, thermal oxidation, or other suitable process. A portion ofinsulating layer 186 is removed by an exposure or development process,LDA, etching, or other suitable process to form openings in theinsulating layer, which expose portions of conductive layer 176 forsubsequent electrical interconnection.

FIG. 4 j also shows an electrically conductive bump material depositedover conductive layer 176, within the openings in insulating layer 186.Bumps 188 are formed over conductive layer 176. Alternatively, if thinfilm 178 includes one RDL layer, such as conductive layer 172, bumps 188are formed over the single RDL layer. Bumps 188 can be formed overconductive layer 172 or 176 or an additional conductive layer. Bumps 188are formed over the area of thin film 178 outside a footprint ofsemiconductor die 124. Bumps 188 can also be formed in the area of thinfilm 178 directly underneath or overlapping with the footprint ofsemiconductor die 124.

Bumps 188 are formed using evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, lead (Pb), Bi, Cu, solder, andcombinations thereof, with an optional flux solution. For example, thebump material can be eutectic Sn/Pb, high-lead solder, or lead-freesolder. The bump material is bonded to conductive layer 176 using asuitable attachment or bonding process. In one embodiment, the bumpmaterial is reflowed by heating the material above its melting point toform spherical balls or bumps 188. In some applications, bumps 188 arereflowed a second time to improve electrical contact to conductive layer176. In one embodiment, bumps 188 are formed over a under bumpmetallization (UBM) having a wetting layer, barrier layer, and adhesivelayer. The bumps can also be compression bonded to conductive layer 176.Bumps 188 represent one type of interconnect structure that can beformed over conductive layer 176. The interconnect structure can alsouse bond wires, conductive paste, stud bump, micro bump, or otherelectrical interconnect.

FIG. 4 j also shows region 190 of thin film 178 where bumps 188 are notformed over conductive layer 176 of thin film 178. Alternatively, bumps188 are formed over conductive layer 176 in region 190 and aresubsequently removed from region 190. In another alternative embodiment,some of bumps 188 are formed and remain in region 190 of thin film 178.Region 190 is configured with bumps 188 or without bumps 188 dependingon the interconnect requirements for the particular semiconductordevice. Region 190 of thin film 178 provides a connection site for asecond semiconductor die or component to be mounted over surface 182 ofthin film 178. In one embodiment, region 190 includes surface 180 ofthin film 178 directly opposite from the area of thin film 178 on whichsemiconductor die 124 is disposed.

Taken together, insulating layers 170, 174, and 186 as well asconductive layers 172, 176, and conductive bumps 188 form interconnectstructure 192. The number of insulating and conductive layers includedwithin interconnect structure 192 depends on, and varies with, thecomplexity of the circuit routing design. Accordingly, interconnectstructure 192 can include one or more insulating and conductive layersto facilitate electrical interconnect with respect to semiconductor die124. Elements that would otherwise be included in a backsideinterconnect structure or RDL can be integrated as part of interconnectstructure 192 to simplify manufacturing and reduce fabrication costswith respect to a package including both front side and backsideinterconnects or RDLs.

In FIG. 4 k, semiconductor die or components 200 are mounted tointerconnect structure 192 over semiconductor die 124 in region 190 ofthin film 178. Each semiconductor die 200 has contact pads formed onactive surface 202 oriented toward semiconductor die 124 and towardsurface 182 of thin film 178 and electrically connected to conductivelayers 172 and 176 of vertical conductive vias 184. Active surface 202contains analog or digital circuits implemented as active devices,passive devices, conductive layers, and dielectric layers formed withinthe die and electrically interconnected according to the electricaldesign and function of the die. For example, the circuit may include oneor more transistors, diodes, and other circuit elements formed withinactive surface 202 to implement analog circuits or digital circuits,such as DSP, ASIC, memory, application processor, or other signalprocessing circuit. Semiconductor die 200 may include discrete devices.Discrete devices can be active devices, such as transistors and diodes,or passive devices, such as capacitors, resistors, and inductors for RFsignal processing. Semiconductor die 200 may also include a packagedsemiconductor die. A plurality of bumps 204 is formed over semiconductordie 200 and reflowed to electrically connect contact pads ofsemiconductor die 200 to conductive layer 176. In one embodiment,semiconductor die 200 is implemented as a flipchip style device. Theheight of semiconductor die 200 disposed on interconnect structure 192is less than or equal to a height of bumps 188 disposed on interconnectstructure 192 outside a footprint of semiconductor die 200. In oneembodiment, the height of bumps 188 exceeds a height of semiconductordie 200.

In FIG. 4 l, an optional underfill material 210 is deposited undersemiconductor die 200. Underfill materials include epoxy, epoxy-resinadhesive material, polymeric materials, films, or other non-conductivematerials. Underfill 210 is non-conductive and environmentally protectsthe semiconductor device from external elements and contaminants.

In one embodiment, after the formation of bumps 188, composite substrateor reconstituted wafer 156 is singulated with saw blade or laser cuttingdevice 212 into individual semiconductor devices 214. By singulatingcomposite substrate 156 before mounting additional semiconductor devicesover the composite substrate, the formation of individual semiconductordevices 214 are accomplished by mounting the additional semiconductordie at the individual device level rather than at the reconstitutedwafer level. Alternatively, composite substrate 156 is singulated afteradditional semiconductor devices are mounted to the composite substrateas shown in FIG. 4 l.

FIG. 4 m shows an individual semiconductor device 214 after singulation.Semiconductor device 214 is a 3D semiconductor structure withsemiconductor die disposed on opposing sides of thin film 178 ofinterconnect structure 192. Semiconductor device 214 including finepitch vertical conductive vias 184 accommodates high densitysemiconductor die, such as wide I/O memory devices, in a flipchiporientation. Semiconductor device 214 also accommodates mixedsemiconductor die sizes. For example, a semiconductor die having memoryfunction and an application processor die can be integrated face-to-faceinto semiconductor device 214. In one embodiment, semiconductor die 124includes an application processor and semiconductor die 200 includesmemory. In another embodiment, semiconductor die 124 includes memory,and semiconductor die 200 includes an application processor.Alternatively, semiconductor die 124 and 200 include other signalprocessing circuits, discrete devices, components, or packaged devices.

Semiconductor die 124 and 200 are electrically connected throughvertical conductive vias 184. Semiconductor device 214 provides verticaldrop-down routing of electrical signals between semiconductor die 124and 200 through the fine pitch vertical conductive vias 184 in thin film178. The electrical conduction path length within semiconductor device214 is reduced to 300 μm or less, and is typically less than 100 μm,which results in a higher speed and more efficient device. The thermalpath length is also reduced. Thin film 178 with semiconductor die 124and 200 disposed on opposing sides reduces the overall package height ofsemiconductor device 214. The thickness of semiconductor device 214 is0.5 millimeters (mm) or less, and is typically as thin as 0.2 mm,whereas the package thickness using a conventional THV substrate is 0.7to 1.4 mm. The smaller package profile of semiconductor device 214improves the thermal performance of the semiconductor device by reducingwarpage and providing a shorter thermal path. The smaller packageprofile of semiconductor device 214 with thin film layers reduces theparasitic capacitance of the 3D semiconductor structure.

FIG. 4 n illustrates an alternative embodiment of semiconductor device214. Semiconductor die or component 216 is mounted to interconnectstructure 192 over semiconductor die 124 in region 190 of thin film 178.Semiconductor die 216 is configured similarly to semiconductor die 200.Semiconductor 216 includes an active surface oriented towardsemiconductor die 124 and toward surface 182 of thin film 178 andelectrically connected to conductive layers 172 and 176 of verticalconductive vias 184. Semiconductor die 216 is disposed on interconnectstructure 192 within a footprint of semiconductor die 124.Alternatively, semiconductor die 216 is disposed partially or entirelyoutside a footprint of semiconductor die 124. Thin film 178 provideselectrical routing capability such that semiconductor die can be mountedto thin film 178 in various configurations. Bumps 188 are formed overthin film 178 in areas of thin film 178 not occupied by semiconductordie 216, or outside a footprint of semiconductor die 216. In oneembodiment, semiconductor die 216 is narrower than semiconductor die124. The shape of semiconductor die 216 leaves space for additionalbumps 188 to be formed over thin film 178. Bumps 188 are formed adjacentto or outside a footprint of semiconductor die 216. Bumps 188 are alsoformed within a footprint of semiconductor die 124 and overlap with thefootprint of semiconductor die 124.

FIGS. 5 a-5 n illustrate a process of forming a Fo-eWLB including a thinfilm interconnect structure having fine pitch interconnects and asemiconductor die mounted over a through-silicon via (TSV) semiconductordie. FIG. 5 a shows a TSV wafer 220 mounted to carrier or temporarysubstrate 222. Carrier 222 contains a sacrificial base material such assilicon, polymer, beryllium oxide, glass, or other suitable low-cost,rigid material for structural support. An interface layer ordouble-sided tape 224 is formed over carrier 222 as a temporary adhesivebonding film, etch-stop layer, or thermal release layer.

TSV wafer 220 includes a base substrate material 226, such as silicon,germanium, gallium arsenide, indium phosphide, or silicon carbide forstructural support. A plurality of semiconductor die or components 228is formed on TSV wafer 220 separated by inter-die wafer area or sawstreets 230. Saw streets 230 provide cutting areas to singulate TSVwafer 220 into individual semiconductor die 228. Semiconductor die 228include active surface 232 and back surface 234 opposite active surface232. Active surface 232 is oriented toward carrier 222. Active surface232 contains analog or digital circuits implemented as active devices,passive devices, conductive layers, and dielectric layers formed withinthe die and electrically interconnected according to the electricaldesign and function of the die. For example, the circuit may include oneor more transistors, diodes, and other circuit elements formed withinactive surface 232 to implement analog circuits or digital circuits,such as DSP, ASIC, memory, application processor, or other signalprocessing circuit. Semiconductor die 228 may include discrete devices.Discrete devices can be active devices, such as transistors and diodes,or passive devices, such as capacitors, resistors, and inductors for RFsignal processing. Semiconductor die 228 may also include a packagedsemiconductor die.

A plurality of vias 236 is formed through substrate 226 using mechanicaldrilling, laser drilling, or deep reactive ion etching (DRIE). Vias 236extend through substrate 226 of TSV wafer 220. Vias 236 are filled withAl, Cu, Sn, Ni, Au, Ag, Ti, tungsten (W), poly-silicon, or othersuitable electrically conductive material using electrolytic plating,electroless plating process, or other suitable metal deposition processto form vertical z-direction conductive TSV.

In FIG. 5 b, a plurality of semiconductor die or components 240 ismounted over TSV wafer 220. Semiconductor die 240 includes activesurface 242 and back surface 244. Active surface 242 contains analog ordigital circuits implemented as active devices, passive devices,conductive layers, and dielectric layers formed within the die andelectrically interconnected according to the electrical design andfunction of the die. For example, the circuit may include one or moretransistors, diodes, and other circuit elements formed within activesurface 242 to implement analog circuits or digital circuits, such asDSP, ASIC, memory, application processor, or other signal processingcircuit. Semiconductor die 240 may also include discrete devices orcomponents such as power transistors, or IPD, such as inductors,capacitors, and resistors, for RF signal processing. Semiconductor die240 may also include a packaged semiconductor die. In one embodiment,semiconductor die 228 includes an application processor andsemiconductor die 240 includes memory. In another embodiment,semiconductor die 228 includes memory, and semiconductor die 240includes an application processor. Alternatively, semiconductor die 228and 240 include other signal processing circuits, discrete devices,components, or packaged devices.

Semiconductor die 240 is disposed over semiconductor die 228 with activesurface 242 oriented toward back surface 234 of semiconductor die 228. Aconductive layer 246 is formed over active surface 242 of semiconductordie 240. Conductive layer 246 is formed using a metal deposition processsuch as Cu foil lamination, printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 246 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, Ti, W, or other suitableelectrically conductive material.

A conductive layer 248 is formed over back surface 234 of semiconductordie 228. Conductive layer 248 is formed using a metal deposition processsuch as Cu foil lamination, printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 248 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, Ti, W, or other suitableelectrically conductive material. Conductive layer 248 contacts or iselectrically connected to vias 236.

An electrically conductive bump material is deposited over conductivelayer 246 or conductive layer 248 using an evaporation, electrolyticplating, electroless plating, ball drop, or screen printing process. Thebump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, andcombinations thereof, with an optional flux solution. For example, thebump material can be eutectic Sn/Pb, high-lead solder, or lead-freesolder. The bump material is bonded to conductive layer 246 and 248using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form balls or bumps 250. In some applications, bumps 250 arereflowed a second time to improve electrical contact to conductive layer246 and 248. Bumps 250 can also be compression bonded orthermocompression bonded to conductive layer 246 and 248. Bumps 250represent one type of interconnect structure that can be formed overconductive layer 246 and 248. The interconnect structure can also usestud bump, micro bump, or other electrical interconnect.

In FIG. 5 c, TSV wafer 220 is singulated through saw street 230 with sawblade or laser cutting tool 260 into individual stacked semiconductordevices 262.

In FIG. 5 d, a second temporary substrate or carrier 264 containssacrificial base material such as silicon, polymer, beryllium oxide, orother suitable low-cost, rigid material for structural support. Aninterface layer or double-sided tape 266 is formed over carrier 264 as atemporary adhesive bonding film or etch-stop layer. Stackedsemiconductor devices 262 are positioned over and mounted to interfacelayer 266 and carrier 264 using a pick and place operation with activesurface 232 of semiconductor die 228 oriented toward the carrier.Stacked semiconductor devices 262 mounted to carrier 264 constitute acomposite substrate or reconstituted wafer 268.

In FIG. 5 e, an encapsulant or molding compound 270 deposited overinterface layer 266 and carrier 264 and over and around stackedsemiconductor devices 262 using a paste printing, compressive molding,transfer molding, liquid encapsulant molding, vacuum lamination,film-assisted molding, or other suitable applicator. Encapsulant 270 isformed over back surface 244 of semiconductor die 240, and can bethinned in a subsequent backgrinding step. Encapsulant 270 can also bedeposited such that the encapsulant is coplanar with back surface 244,and does not cover back surface 244. Encapsulant 270 can be polymercomposite material, such as epoxy resin with filler, epoxy acrylate withfiller, or polymer with proper filler. Encapsulant 270 isnon-conductive, provides physical support, and environmentally protectsthe semiconductor device from external elements and contaminants.

FIG. 5 f shows composite substrate or reconstituted wafer 268 covered byencapsulant 270. In FIG. 5 f, surface 272 of encapsulant 270 undergoesan optional grinding operation with grinder 274 to planarize the surfaceand reduce thickness of the encapsulant. A chemical etch can also beused to remove and planarize encapsulant 270. FIG. 5 g shows a portionof encapsulant 270 removed to expose back surface 244 of semiconductordie 240.

In FIG. 5 g, carrier 264 and interface layer 266 are removed fromcomposite substrate 268 by chemical etching, mechanical peeling, CMP,mechanical grinding, thermal bake, UV light, laser scanning, or wetstripping to facilitate the formation of an interconnect structure overactive surface 232 of semiconductor die 228 and encapsulant 270 around aperiphery of the semiconductor die.

In FIG. 5 h, an insulating or passivation layer 280 is formed oversemiconductor die 228 and encapsulant 270. Insulating layer 280 containsone or more layers of low temperature curable polymer dielectric resist(i.e., cures at less than 260 degrees C.) with or without filler, SiO2,Si3N4, SiON, Ta2O5, Al2O3, or other material having similar insulatingand structural properties. Insulating layer 170 is deposited using PVD,CVD, printing, spin coating, spray coating, sintering, thermaloxidation, or other suitable process. Insulating layer 280 has athickness of less than 10 μm and is typically as thin as 4 μm. A portionof insulating layer 280 is removed by an exposure or developmentprocess, LDA, etching, or other suitable process to form openings overactive surface 232. The openings expose portions of active surface 232of semiconductor die 228 and vias 236 for subsequent electricalinterconnect.

In FIG. 5 i, an electrically conductive layer 282 is patterned anddeposited over insulating layer 280, over semiconductor die 228, anddisposed within the openings in insulating layer 280 to fill theopenings and contact active surface 232 and vias 236. The one or morelayers of conductive layer 282 include Al, Cu, Sn, Ni, Au, Ag, Ti/Cu,TiW/Cu, Ti/NiV/Cu, TiW/NiV/Cu, or other suitable electrically conductivematerial. The deposition of conductive layer 282 uses PVD, CVD,electrolytic plating, electroless plating, or other suitable process.Conductive layer 282 has a thickness of less than 15 μm and is typicallyas thin as 3 μm. Conductive layer 282 operates as an RDL to fan-out andextend electrical connection from stacked semiconductor device 262 topoints external to stacked semiconductor device 262. One portion ofconductive layer 282 is electrically connected to contact pads on activesurface 232 of semiconductor die 228. Another portion of conductivelayer 282 is electrically connected to vias 236. Other portions ofconductive layer 282 can be electrically common or electrically isolateddepending on the design and function of stacked semiconductor device262.

In FIG. 5 j, an insulating or passivation layer 284 is formed overinsulating layer 280 and conductive layer 282. Insulating layer 284contains one or more layers of low temperature curable polymerdielectric resist (i.e., cures at less than 260 degrees C.) with orwithout filler, SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other materialhaving similar insulating and structural properties. Insulating layer284 is deposited using PVD, CVD, printing, spin coating, spray coating,sintering, thermal oxidation, or other suitable process. Insulatinglayer 284 has a thickness of less than 10 μm and is typically as thin as4 μm. A portion of insulating layer 284 is removed by an exposure ordevelopment process, LDA, etching, or other suitable process to formopenings in the insulating layer, which expose portions of conductivelayer 282 for subsequent electrical interconnection.

In FIG. 5 k, an electrically conductive layer 286 is patterned anddeposited over insulating layer 284, over conductive layer 282, anddisposed within the openings in insulating layer 284 as one or morelayers, including seed layers, to fill the openings and contact andelectrically connect to conductive layer 282. The one or more layers ofconductive layer 176 include Al, Cu, Sn, Ni, Au, Ag, Ti/Cu, TiW/Cu,Ti/NiV/Cu, TiW/NiV/Cu, or other suitable electrically conductivematerial. The deposition of conductive layer 286 uses PVD, CVD,electrolytic plating, electroless plating, or other suitable process.Conductive layer 286 has a thickness of less than 15 μm and is typicallyas thin as 3 μm. In one embodiment, the deposition of conductive layer286 includes selective plating with a seed layer and lithography.Conductive layer 286 operates as an RDL to fan-out and extend electricalconnection from stacked semiconductor device 262 to points external tostacked semiconductor device 262.

Insulating layers 280 and 284 together with conductive layers 282 and286 form thin film 288. Thin film 288 constitutes an interconnectstructure. In an alternative embodiment, thin film 288 may include asfew as one conductive layer, such as conductive layer 282. In anotheralternative embodiment, thin film 288 includes two or more RDL layers,such as conductive layers 282 and 286 and additional conductive layerssimilar to conductive layers 282 and 286. Thin film 288 may include asmany insulating and conductive layers as necessary for the interconnectdensity and electrical routing needed for the particular semiconductordevice.

Thin film 288 includes surface 290 over which stacked semiconductordevice 262 is disposed and surface 292 opposite surface 290. Thin film288 has a thickness less than 50 μm, which is thinner than aconventional THV substrate which typically has a thickness of 250 to 350μm. Thin film 288 is formed from layers of insulating and conductivematerial which can each be formed with a thickness of less than 10 μm.The thin layers of insulating and conductive material allow horizontaland vertical interconnects to be formed in close proximity to adjacenthorizontal and vertical interconnects within the thin layers (e.g., witha pitch of less than 50 μm). With horizontal and vertical interconnectsformed in close proximity to adjacent interconnects, a higher density ofinterconnects is achieved within the interconnect structure. Becausethin film 288 includes higher density interconnects, thin film 288provides more flexibility in integration of semiconductor devices intothe 3D semiconductor structure. The high density interconnect structureaccommodates semiconductor die with varying bump pitch, for example,semiconductor die from multiple manufacturing sources.

Conductive layers 282 and 286 form horizontal and verticalinterconnections or vertical conductive vias 294 through thin film 288.Horizontal and vertical interconnections are formed as close together asnecessary for connection to a semiconductor die or component or forrouting electrical signals through thin film 288. For example,conductive layers 282 and 286 may include conductive traces. A firstconductive trace is formed in close proximity to a second conductivetrace (e.g., a pitch between conductive traces is less than 50 μm). Thefine pitch between conductive traces allows space for more conductivetraces to be formed within thin film 288, while the thinness of eachthin film layer reduces the thickness of the interconnect structurecompared to a conventional THV substrate.

Conductive layers 282 and 286 also form vertical conductive vias 294 inwhich a first vertical conductive via is formed in close proximity to asecond vertical conductive via (e.g., a pitch between verticalconductive vias is less than 50 μm). Conductive layer 282 includes afirst portion of vertical conductive vias 294, and conductive layer 286includes a second portion of vertical conductive vias 294. Verticalconductive vias 294 may extend from surface 290 to surface 292 of thinfilm 288 or vertical conductive vias 294 may be formed partially throughthin film 288. A pitch P between vertical conductive vias 294 is lessthan 50 μm. The pitch P between vertical conductive vias 294 in thinfilm 288 is finer than the pitch between conductive vias in aconventional THV substrate, which is typically 100 μm or greater.

The fine pitch horizontal and vertical interconnections in thin film 288provides a higher interconnect density and I/O terminal count. Thin film288 provides an interconnect pitch which allows high densitysemiconductor die to be mounted to thin film 288 in a flipchiporientation. Additional semiconductor die can be mounted in aface-to-back orientation over thin film 288. Thin film 288 extendsbeyond a footprint of semiconductor die 228 in a fan-out design tofurther increase the I/O terminal count. The thinness of thin film 288allows for a smaller and thinner overall semiconductor device package,which reduces warpage and increase the speed of the device. Further, thehigh density interconnects accommodates more electrical signals per 3Dsemiconductor structure and improves the compatibility of theinterconnect structure with a greater variety of semiconductor deviceand components types.

In FIG. 5 l, an optional insulating or passivation layer 296 is formedover insulating layer 284 and conductive layer 286. Insulating layer 296contains one or more layers of low temperature curable polymerdielectric resist (i.e., cures at less than 260 degrees C.) with orwithout filler, SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other materialhaving similar insulating and structural properties. Insulating layer296 is deposited using PVD, CVD, printing, spin coating, spray coating,sintering, thermal oxidation, or other suitable process. A portion ofinsulating layer 296 is removed by an exposure or development process,LDA, etching, or other suitable process to form openings in theinsulating layer, which expose portions of conductive layer 286 forsubsequent electrical interconnection.

FIG. 5 l also shows an electrically conductive bump material depositedover conductive layer 286, within the openings in insulating layer 296.Bumps 298 are formed over conductive layer 296. Alternatively, if thinfilm 288 includes one RDL layer, such as conductive layer 282, bumps 298are formed over the single RDL layer. Bumps 298 can be formed overconductive layer 282 or 284 or an additional conductive layer. Bumps 298are formed over the area of thin film 288 outside a footprint of stackedsemiconductor device 262. Bumps 298 can also be formed in the area ofthin film 288 directly underneath stacked semiconductor device 262. Inone embodiment, bumps 298 are formed within a footprint of stackedsemiconductor device 262 and overlap with the footprint of stackedsemiconductor device 262.

Bumps 298 are formed using evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 286 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 298. In some applications, bumps 298 are reflowed a second time toimprove electrical contact to conductive layer 286. In one embodiment,bumps 298 are formed over a UBM having a wetting layer, barrier layer,and adhesive layer. The bumps can also be compression bonded toconductive layer 286. Bumps 298 represent one type of interconnectstructure that can be formed over conductive layer 286. The interconnectstructure can also use bond wires, conductive paste, stud bump, microbump, or other electrical interconnect.

Taken together, insulating layers 280, 284, and 296 as well asconductive layers 282, 286, and conductive bumps 298 form interconnectstructure 300. The number of insulating and conductive layers includedwithin interconnect structure 300 depends on, and varies with, thecomplexity of the circuit routing design. Accordingly, interconnectstructure 300 can include one or more insulating and conductive layersto facilitate electrical interconnect with respect to stackedsemiconductor device 262. Elements that would otherwise be included in abackside interconnect structure or RDL can be integrated as part ofinterconnect structure 300 to simplify manufacturing and reducefabrication costs with respect to a package including both front sideand backside interconnects or RDLs.

In FIG. 5 m, composite substrate or reconstituted wafer 268 issingulated with saw blade or laser cutting device 302 into individualsemiconductor devices 304.

FIG. 5 n shows an individual semiconductor device 304 after singulation.Semiconductor device 304 is a 3D semiconductor structure with stackedsemiconductor die disposed on thin film 288 of interconnect structure300. Semiconductor die 228 and semiconductor die 240 are electricallyconnected to vertical conductive vias 294. Semiconductor die 240 iselectrically connected to vertical conductive vias 294 throughconductive layers 246 and 248, conductive bumps 250, and vias 236 ofsemiconductor die 228. Semiconductor die 228 and 240 electricallyconnect to external devices through vertical conductive vias 294.Semiconductor device 304 including fine pitch vertical conductive vias294 accommodates high density semiconductor die, such as wide I/O memorydevices, in a flipchip orientation over a TSV semiconductor die.Semiconductor device 304 also accommodates mixed semiconductor diesizes. For example, a semiconductor die having memory function and anapplication processor die can be integrated face-to-back intosemiconductor device 304.

Semiconductor device 304 provides vertical drop-down routing ofelectrical signals for semiconductor die 228 and 240 through the finepitch vertical conductive vias 294 in thin film 288 of interconnectstructure 300. The electrical conduction path length between stackedsemiconductor device 262 and external devices is reduced to 300 μm orless which results in a higher speed and more efficient device. Thethermal path length is also reduced. Thin film 288 reduces the overallpackage height of semiconductor device 304. The thickness ofsemiconductor device 304 is 0.5 mm or less, and is typically as thin as0.2 mm, whereas the package thickness using a conventional THV substrateis 0.7 to 1.4 mm. The smaller package profile of semiconductor device304 improves the thermal performance of the semiconductor device byreducing warpage and providing a shorter thermal path. The smallerpackage profile of semiconductor device 304 with thin film layersreduces the parasitic capacitance of the 3D semiconductor structure.

FIGS. 6 a-6 g illustrate an alternative embodiment of the process offorming a Fo-eWLB over which a thin film interconnect structure can beformed having fine pitch interconnects. FIG. 6 a shows a TSVsemiconductor die 310 mounted to carrier or temporary substrate 312.Carrier 312 contains a sacrificial base material such as silicon,polymer, beryllium oxide, glass, or other suitable low-cost, rigidmaterial for structural support. An interface layer or double-sided tape314 is formed over carrier 312 as a temporary adhesive bonding film,etch-stop layer, or thermal release layer.

Semiconductor die 310 includes a base substrate material 316, such assilicon, germanium, gallium arsenide, indium phosphide, or siliconcarbide for structural support. Semiconductor die 310 include activesurface 318 and back surface 320 opposite active surface 318. Activesurface 318 is oriented toward carrier 312. Active surface 318 containsanalog or digital circuits implemented as active devices, passivedevices, conductive layers, and dielectric layers formed within the dieand electrically interconnected according to the electrical design andfunction of the die. For example, the circuit may include one or moretransistors, diodes, and other circuit elements formed within activesurface 318 to implement analog circuits or digital circuits, such asDSP, ASIC, memory, application processor, or other signal processingcircuit. Semiconductor die 310 may include discrete devices. Discretedevices can be active devices, such as transistors and diodes, orpassive devices, such as capacitors, resistors, and inductors for RFsignal processing. Semiconductor die 310 may also include a packagedsemiconductor die.

A plurality of vias 322 is formed through substrate 226 using mechanicaldrilling, laser drilling, or deep reactive ion etching (DRIE). Vias 322extend through substrate 316. Vias 322 are filled with Al, Cu, Sn, Ni,Au, Ag, Ti, tungsten (W), poly-silicon, or other suitable electricallyconductive material using electrolytic plating, electroless platingprocess, or other suitable metal deposition process to form verticalz-direction conductive TSV. Semiconductor die 310 disposed overinterface layer 314 and carrier 312 constitutes composite substrate orreconstituted wafer 324.

In FIG. 6 b, an encapsulant or molding compound 330 deposited overinterface layer 314 and carrier 312 and over and around semiconductordie 310 using a paste printing, compressive molding, transfer molding,liquid encapsulant molding, vacuum lamination, film-assisted molding, orother suitable applicator. Encapsulant 330 is formed over back surface320 of semiconductor die 310, and can be thinned in a subsequentbackgrinding step. Encapsulant 330 can also be deposited such that theencapsulant is coplanar with back surface 320, and does not cover backsurface 320. Encapsulant 330 can be polymer composite material, such asepoxy resin with filler, epoxy acrylate with filler, or polymer withproper filler. Encapsulant 330 is non-conductive, provides physicalsupport, and environmentally protects the semiconductor device fromexternal elements and contaminants.

FIG. 6 c shows composite substrate or reconstituted wafer 324 covered byencapsulant 330. In FIG. 6 c, surface 332 of encapsulant 330 undergoesan optional grinding operation with grinder 334 to planarize the surfaceand reduce thickness of the encapsulant. A chemical etch can also beused to remove and planarize encapsulant 330. FIG. 6 c shows a portionof encapsulant 330 removed to expose back surface 320 of semiconductordie 310.

In FIG. 6 d, semiconductor die or components 340 is mounted oversemiconductor die 310. Semiconductor die 340 includes active surface 342and back surface 344. Active surface 342 contains analog or digitalcircuits implemented as active devices, passive devices, conductivelayers, and dielectric layers formed within the die and electricallyinterconnected according to the electrical design and function of thedie. For example, the circuit may include one or more transistors,diodes, and other circuit elements formed within active surface 342 toimplement analog circuits or digital circuits, such as DSP, ASIC,memory, application processor, or other signal processing circuit.Semiconductor die 340 may include discrete devices. Discrete devices canbe active devices, such as transistors and diodes, or passive devices,such as capacitors, resistors, and inductors for RF signal processing.Semiconductor die 340 may also include a packaged semiconductor die. Inone embodiment, semiconductor die 310 includes an application processorand semiconductor die 340 includes memory. In another embodiment,semiconductor die 310 includes memory, and semiconductor die 340includes an application processor. Alternatively, semiconductor die 310and 340 include other signal processing circuits, discrete devices,components, or packaged devices.

Semiconductor die 340 is disposed over semiconductor die 228 with activesurface 342 oriented toward back surface 320 of semiconductor die 310. Aconductive layer 346 is formed over active surface 342 of semiconductordie 340. Conductive layer 346 is formed using a metal deposition processsuch as Cu foil lamination, printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 346 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, Ti, W, or other suitableelectrically conductive material.

A conductive layer 348 is formed over back surface 320 of semiconductordie 310. Conductive layer 348 is formed using a metal deposition processsuch as Cu foil lamination, printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 348 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, Ti, W, or other suitableelectrically conductive material. Conductive layer 348 contacts or iselectrically connected to vias 322.

An electrically conductive bump material is deposited over conductivelayer 346 or conductive layer 348 using an evaporation, electrolyticplating, electroless plating, ball drop, or screen printing process. Thebump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, andcombinations thereof, with an optional flux solution. For example, thebump material can be eutectic Sn/Pb, high-lead solder, or lead-freesolder. The bump material is bonded to conductive layer 346 and 348using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form balls or bumps 350. In some applications, bumps 350 arereflowed a second time to improve electrical contact to conductive layer346 and 348. Bumps 350 can also be compression bonded orthermocompression bonded to conductive layer 346 and 348. Bumps 350represent one type of interconnect structure that can be formed overconductive layer 346 and 348. The interconnect structure can also usestud bump, micro bump, or other electrical interconnect.

An optional encapsulant or molding compound, not shown in FIGS. 6 a-6 g,can be deposited over and around semiconductor die 340 using a pasteprinting, compressive molding, transfer molding, liquid encapsulantmolding, vacuum lamination, film-assisted molding, or other suitableapplicator. The optional encapsulant is similar to encapsulant 330 andcan be formed over back surface 344 of semiconductor die 340 and oversemiconductor die 310 and encapsulant 330.

In FIG. 6 e, carrier 312 and interface layer 314 are removed fromcomposite substrate 324 by chemical etching, mechanical peeling, CMP,mechanical grinding, thermal bake, UV light, laser scanning, or wetstripping to facilitate the formation of an interconnect structure overactive surface 318 of semiconductor die 310 and encapsulant 330 around aperiphery of the semiconductor die.

The process of forming a thin film interconnect structure over thesurface of composite substrate 324 in FIG. 6 e proceeds as shown inFIGS. 5 h-5 l to produce composite substrate 324 including a thin filminterconnect structure as shown in FIG. 6 f.

In FIG. 6 f, an insulating or passivation layer 360 is similar toinsulating layer 280 and is formed over semiconductor die 310 andencapsulant 330. Insulating layer 360 has a thickness of less than 10 μmand is typically as thin as 4 μm. A portion of insulating layer 360 isremoved by an exposure or development process, LDA, etching, or othersuitable process to form openings over active surface 318. The openingsexpose portions of active surface 318 of semiconductor die 310 and vias322 for subsequent electrical interconnect.

An electrically conductive layer 362 is similar to conductive layer 282and is deposited over insulating layer 360, over semiconductor die 310,and disposed within the openings in insulating layer 280 to fill theopenings and contact active surface 318 and vias 322. Conductive layer362 has a thickness of less than 15 μm and is typically as thin as 3 μm.Conductive layer 362 operates as an RDL to fan-out and extend electricalconnection from semiconductor die 310 and 340 to points external tosemiconductor die 310 and 340. One portion of conductive layer 362 iselectrically connected to contact pads on active surface 318 ofsemiconductor die 310. Another portion of conductive layer 362 iselectrically connected to vias 322. Other portions of conductive layer362 can be electrically common or electrically isolated depending on thedesign and function of semiconductor die 310 and 340.

An insulating layer or passivation layer 364 is similar to insulatinglayer 284 and is formed over insulating layer 360 and conductive layer362. Insulating layer 364 has a thickness of less than 10 μm and istypically as thin as 4 μm. A portion of insulating layer 364 is removedby an exposure or development process, LDA, etching, or other suitableprocess to form openings in the insulating layer, which expose portionsof conductive layer 362 for subsequent electrical interconnection.

An electrically conductive layer 366 is similar to conductive layer 286and is deposited over insulating layer 364, over conductive layer 362,and disposed within the openings in insulating layer 364 as one or morelayers, including seed layers, to fill the openings and contact andelectrically connect to conductive layer 362. Conductive layer 366 has athickness of less than 15 μm and is typically as thin as 3 μm. In oneembodiment, the deposition of conductive layer 366 includes selectiveplating with a seed layer and lithography. Conductive layer 366 operatesas an RDL to fan-out and extend electrical connection from semiconductordie 310 and 340 to points external to semiconductor die 310 and 340.

Insulating layers 360 and 364 together with conductive layers 362 and366 form thin film 368 which is similar to thin film 288. Thin film 368constitutes an interconnect structure. In an alternative embodiment,thin film 368 may include as few as one conductive layer, such asconductive layer 362. Thin film 368 may include as many insulating andconductive layers as necessary for the interconnect density andelectrical routing needed for the particular semiconductor device.

Thin film 368 includes surface 370 over which semiconductor die 310 and340 are disposed and surface 372 opposite surface 370. Thin film 368 hasa thickness less than 50 μm, which is thinner than a conventional THVsubstrate which typically has a thickness of 250 to 350 μm. Thin film368 is formed from layers of insulating and conductive material whichcan each be formed with a thickness of less than 10 μm. The thin layersof insulating and conductive material allow horizontal and verticalinterconnects to be formed in close proximity to adjacent horizontal andvertical interconnects within the thin layers (e.g., with a pitch ofless than 50 μm). With horizontal and vertical interconnects formed inclose proximity to adjacent interconnects, a higher density ofinterconnects is achieved within the interconnect structure. Becausethin film 368 includes higher density interconnects, thin film 368provides more flexibility in integration of semiconductor devices intothe 3D semiconductor structure. The high density interconnect structureaccommodates semiconductor die with varying bump pitch, for example,semiconductor die from multiple manufacturing sources.

Conductive layers 362 and 366 form horizontal and verticalinterconnections or vertical conductive vias 374 through thin film 368.Horizontal and vertical interconnections are formed as close together asnecessary for connection to a semiconductor die or component or forrouting electrical signals through thin film 368. For example,conductive layers 362 and 366 may include conductive traces. A firstconductive trace is formed in close proximity to a second conductivetrace (e.g., a pitch between conductive traces is less than 50 μm). Thefine pitch between conductive traces allows space for more conductivetraces to be formed within thin film 368, while the thinness of eachthin film layer reduces the thickness of the interconnect structurecompared to a conventional THV substrate.

Conductive layers 362 and 366 also form vertical conductive vias 374 inwhich a first vertical conductive via is formed in close proximity to asecond vertical conductive via (e.g., a pitch between verticalconductive vias is less than 50 μm). Conductive layer 362 includes afirst portion of vertical conductive vias 374, and conductive layer 366includes a second portion of vertical conductive vias 374. Verticalconductive vias 374 may extend from surface 370 to surface 372 of thinfilm 368 or vertical conductive vias 374 may be formed partially throughthin film 368. A pitch between vertical conductive vias 374 is less than50 μm. The pitch between vertical conductive vias 374 in thin film 368is finer than the pitch between conductive vias in a conventional THVsubstrate, which is typically 100 μm or greater.

The fine pitch horizontal and vertical interconnections in thin film 368provides a higher interconnect density and I/O terminal count. Thin film368 provides an interconnect pitch which allows high densitysemiconductor die to be mounted to thin film 368 in a flipchiporientation. Additional semiconductor die can be mounted in aface-to-back orientation over thin film 368. Thin film 368 extendsbeyond a footprint of semiconductor die 310 and 340 in a fan-out designto further increase the I/O terminal count. The thinness of thin film368 allows for a smaller and thinner overall semiconductor devicepackage, which reduces warpage and increases the speed of the device.Further, the high density interconnects accommodates more electricalsignals per 3D semiconductor structure and improves the compatibility ofthe interconnect structure with a greater variety of semiconductordevice and components types.

An optional insulating or passivation layer 376 is similar to insulatinglayer 296 and is formed over insulating layer 364 and conductive layer366. An electrically conductive bump material is deposited overconductive layer 366, within the openings in insulating layer 376. Bumps378 are formed over conductive layer 366. Alternatively, if thin film368 includes one RDL layer, such as conductive layer 362, bumps 378 areformed over the single RDL layer. Bumps 378 can be formed overconductive layer 362 or 364 or an additional conductive layer. Bumps 378are formed over the area of thin film 368 outside a footprint ofsemiconductor die 310 and 340. Bumps 378 are similar to bumps 298 andcan be formed in the area of thin film 368 directly underneath oroverlapping with the footprint of semiconductor die 310 and 340. In oneembodiment, bumps 378 are formed within a footprint of semiconductor die310 and 340 and overlap with the footprint of semiconductor die 310 and340. Bumps 378 represent one type of interconnect structure that can beformed over conductive layer 366. The interconnect structure can alsouse bond wires, conductive paste, stud bump, micro bump, or otherelectrical interconnect.

Taken together, insulating layers 360, 364, and 376 as well asconductive layers 362, 366, and conductive bumps 378 form interconnectstructure 380. The number of insulating and conductive layers includedwithin interconnect structure 380 depends on, and varies with, thecomplexity of the circuit routing design. Accordingly, interconnectstructure 380 can include one or more insulating and conductive layersto facilitate electrical interconnect with respect to semiconductor die310 and 340. Elements that would otherwise be included in a backsideinterconnect structure or RDL can be integrated as part of interconnectstructure 380 to simplify manufacturing and reduce fabrication costswith respect to a package including both front side and backsideinterconnects or RDLs.

Composite substrate or reconstituted wafer 324 is singulated with sawblade or laser cutting device 382 into individual semiconductor devices384.

FIG. 6 g shows an individual semiconductor device 384 after singulation.Semiconductor device 384 is a 3D semiconductor structure with stackedsemiconductor die disposed on thin film 368 of interconnect structure380. Semiconductor die 310 and semiconductor die 340 are electricallyconnected to vertical conductive vias 374. Semiconductor die 340 iselectrically connected to vertical conductive vias 374 throughconductive layers 346 and 348, conductive bumps 350, and vias 322 ofsemiconductor die 310. Semiconductor die 310 and 340 electricallyconnect to external devices through vertical conductive vias 374.Semiconductor device 384 including fine pitch vertical conductive vias374 accommodates high density semiconductor die, such as wide I/O memorydevices, in a flipchip orientation over a TSV semiconductor die.Semiconductor device 384 also accommodates mixed semiconductor diesizes. For example, a semiconductor die having memory function and anapplication processor die can be integrated face-to-back intosemiconductor device 384.

Semiconductor device 384 provides vertical drop-down routing ofelectrical signals for semiconductor die 310 and 340 through the finepitch vertical conductive vias 374 in thin film 368 of interconnectstructure 380. The electrical conduction path length betweensemiconductor die 310 and 340 and external devices is reduced to 300 μmor less which results in a higher speed and more efficient device. Thethermal path length is also reduced. Thin film 368 reduces the overallpackage height of semiconductor device 384. The thickness ofsemiconductor device 384 is 0.5 mm or less, and is typically as thin as0.2 mm, whereas the package thickness using a conventional THV substrateis 0.7 to 1.4 mm. The smaller package profile of semiconductor device384 improves the thermal performance of the semiconductor device byreducing warpage and providing a shorter thermal path. The smallerpackage profile of semiconductor device 384 with thin film layersreduces the parasitic capacitance of the 3D semiconductor structure.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A method of making a semiconductor device,comprising: providing a plurality of first semiconductor die; depositingan encapsulant over a first surface of the first semiconductor die andaround the first semiconductor die; forming an insulating layer over theencapsulant and over a second surface of the first semiconductor dieopposite the first surface; forming a first conductive layer over theinsulating layer; and disposing a second semiconductor die over thefirst semiconductor die and electrically connected to the firstconductive layer.
 2. The method of claim 1, further including forming asecond conductive layer over the first conductive layer to form verticalconductive vias.
 3. The method of claim 2, wherein a pitch betweenvertical conductive vias is less than 50 micrometers.
 4. The method ofclaim 1, further including forming a bump over the first conductivelayer and overlapping a footprint of the first semiconductor die.
 5. Themethod of claim 1, further including forming a bump over the firstconductive layer outside a footprint of the first semiconductor die. 6.The method of claim 1, further including disposing the secondsemiconductor die over the second surface of the first semiconductordie.
 7. A method of making a semiconductor device, comprising: providinga first semiconductor die; depositing an encapsulant over the firstsemiconductor die; forming an insulating layer including openings overthe first semiconductor die; forming a first conductive layer over thefirst semiconductor die; and disposing a second semiconductor die overthe first semiconductor die and electrically connected to the firstconductive layer.
 8. The method of claim 7, wherein a pitch betweenopenings of the insulating layer is less than 50 micrometers.
 9. Themethod of claim 7, further including forming a through-silicon via (TSV)through the first semiconductor die.
 10. The method of claim 9, furtherincluding disposing the second semiconductor die over a back surface ofthe first semiconductor die.
 11. The method of claim 7, furtherincluding forming a second conductive layer over the first conductivelayer.
 12. The method of claim 7, wherein the first and secondsemiconductor die electrically connect through the first conductivelayer.
 13. The method of claim 7, further including forming a bump overthe first conductive layer outside a footprint of the firstsemiconductor die.
 14. A method of making a semiconductor device,comprising: providing a first semiconductor die; forming a firstinsulating layer over the first semiconductor die; forming a firstconductive layer over the first semiconductor die; and disposing asecond semiconductor die over the first semiconductor die.
 15. Themethod of claim 14, further including forming an interconnect structureby forming a second conductive layer over the first conductive layer.16. The method of claim 15, wherein a thickness of the interconnectstructure is less than 50 micrometers.
 17. The method of claim 15,wherein the first and second conductive layers form a plurality ofinterconnects.
 18. The method of claim 17, wherein a pitch betweeninterconnects is less than 50 micrometers.
 19. The method of claim 17,further including electrically connecting the first semiconductor die tothe second semiconductor die through the interconnects.
 20. The methodof claim 14, further including disposing the second semiconductor dieover an active surface of the first semiconductor die.
 21. Asemiconductor device, comprising: a first semiconductor die; a firstinsulating layer including openings formed over the first semiconductordie; a first conductive layer formed the first semiconductor die; and asecond semiconductor die disposed over the first semiconductor die. 22.The semiconductor device of claim 21, wherein the first and secondsemiconductor die electrically connect through the first conductivelayer.
 23. The semiconductor device of claim 21, further including abump formed over the first conductive layer outside a footprint of thefirst semiconductor die.
 24. The semiconductor device of claim 21,further including the second semiconductor die disposed over an activesurface of the first semiconductor die.
 25. The semiconductor device ofclaim 21, further including a through-silicon via (TSV) formed throughthe first semiconductor die.